The present invention relates to a temperature-gradient type multistage condenser of a gas/liquid separator for separating solvent vapor having solutes into gas and liquid, and for recovering solvents. The solvent vapor to be separated has been produced by a rotary evaporator, a test tube sample concentrator or the like.
Recently, standards and regulations for discharge of various solvents used at research laboratories and the like have been strictly regulated and have also been tightened in many countries to protect environments. However, conventional gas/liquid separators had a low solvent recovering ratio and were unable to satisfy strict discharge standards. Therefore, at research laboratories and the like, so as to satisfy strict discharge regulations, a plurality of trapping apparatuses were required to be connected in series with a conventional gas/liquid separator so as to perform solvent recovery operations several times when recovering a solvent from solvent vapor.
In a conventional gas/liquid separator, solvent vapor generated from a rotary evaporator, a test-tube sample concentrator or the like is cooled by a dewar type condenser, a vertical type condenser or the like to perform gas/liquid separation. The dewar type condenser is used to recover non-solidifying solvents having low melting points, such as diethyl ether or dichloromethane. The vertical type condenser is used to recover solidifying solvents, such as benzene having a solidifying point of +5.5.degree. C. Therefore, it was necessary to select an appropriate condenser depending on the kind of solvent when conventional solvent recovery was performed.
Furthermore, in conventional gas/liquid separators, solvent recovery cannot be performed completely. Therefore, it is preferable that a diaphragm type vacuum pump having TEFLON.RTM. (polytetrafluorethylene) valves should be used as a vacuum source. However, since the diaphragm type vacuum pump having TEFLON.RTM. valves are expensive, they do not become widespread. In actual practice, water flow pumps have been used widely. This causes the problem of environmental pollution.
FIG. 11 is a system diagram showing a solvent recovery system comprising a conventional gas/liquid separator. The conventional gas/liquid separator shown in FIG. 11 is a rotary evaporator 100 comprising a dewar type condenser 101 shown in cross section. This rotary evaporator 100 is structured so that a sample flask 102 held at a holding portion 104 can be moved up and down by a jack. The sample flask 102 is immersed in a bath portion 103, and a sample in the sample flask 102 becomes solvent vapor. The solvent vapor is introduced into the dewar type condenser 101. The solvent vapor introduced from the bottom portion of the dewar type condenser 101 passes through the side wall passage of the dewar type condenser 101, and is discharged from an exhaust port 101a.
Dry ice or the like used as a freezing mixture is stored in the dewar type condenser 101. In the dewar type condenser 101, solvent vapor is liquefied and trapped in a receiving flask 105.
As shown in FIG. 11, three trapping apparatuses 110, 111, 112 are connected in series with the exhaust port 101a of the dewar type condenser 101. These trapping apparatuses have vacuum traps 110a, 111a, 112a, and dewar bottles 110b, 111b, 112b for trapping. The vacuum traps 110a, 111a, 112a are provided for evaporating a solvent from solvent vapor. The dewar bottles 110b, 111b, 112b are provided for cooling and maintaining the vacuum traps 110a, 111a, 112a, respectively at predetermined temperatures. In the trapping apparatuses 110, 111, 112, acetone and dry ice are used as a freezing mixture.
The exhaust port of the last trapping apparatus 112 is connected to an aspirator (water-jet pump) 114, which is used as a vacuum source, via a pressure gauge 113 and a T-shaped pipe. In addition, the T-shaped pipe is connected to a needle valve 116 via a leak valve 115.
As described above, in the conventional gas/liquid separator, the condenser of the gas/liquid separator must be selected depending on the kind of solvent to be recovered. Therefore, the solvent recovery requires very troublesome operations.
Furthermore, since the solvent recovery ratio attained by a single gas/liquid separator is low in the conventional gas/liquid separator, if an aspirator (water-jet pump) is used as a vacuum source, drain water may be contaminated. And if a diaphragm type vacuum pump with TEFLON.RTM. valves is used as a vacuum source, the environment in a laboratory may be harmed, thereby causing problems in safety.
Moreover, in order to satisfy strict discharge regulations and standards by using the conventional gas/liquid separator, a plurality of trapping apparatuses must be connected in series with the conventional gas/liquid separator, and a plurality of solvent recovery operations must be performed. Therefore, the conventional gas/liquid separator takes much more time and cost for solvent recovery, and requires a wide space for installing such a gas/liquid separator system.
Accordingly, an object of the present invention is to provide a temperature-gradient type multistage condenser having a high solvent recovery ratio and superior operability.
Another object of the present invention is to provide a temperature-gradient type multistage condenser capable of securely recovering various solvents by using a single gas/liquid separator and capable of satisfying strict discharge regulations.
A still another object of the present invention is to provide a gas/liquid separator having compatibility with the conventional gas/liquid separator and capable of greatly increasing the solvent recovery ratio attained by the conventional gas/liquid separator by replacing a part of the conventional gas/liquid separator with the temperature-gradient type multistage condenser of the present invention.
A still yet another object of the present invention is to provide a gas/liquid separator having an easy-to-produce structure which is produceable in a short time at cost much lower than that of the conventional gas/liquid separator.